Engine fuel system



Nov. 10, 1959 E. F. GRIEP 2,911,958

ENGINE FUEL SYSTEM Filed Oct. 12, 1956 INJECTORS "I INJECTORS I l l 4 mi P g g; v 15 24 1 a2 ACCUMULATOR X21 U K T DISTILLATE RESIDUUM m; l112* Ii] |i| If] {/24 I m i INJECTORS I LTJ Q i] ACCUMULATOR INVENTORELZER F. GR/EP BY :2

ATTORNEYS United States Patent ENGINE FUEL SYSTEM Elmer F. Griep,Berkeley, Calif., assignor, by niesne assignments, to CaliforniaResearch Corporation, San Francisco, Calif., a corporation of DelawareApplication October 12, 1956, Serial No. 615,539

6 Claims. (Cl. 123-30) This invention relates to a fuel supply systemfor an internal combustion engine of the compression-ignition type thatis being selectively operated upon one or both of two dissimilar liquidfuels, and particularly refers to a method and apparatus forsequestering a predetermined quantity of the fuel from the supply systemand for rapidly transferring the fuel supply to a desired fuel sourceupon a predetermined change of operating conditions of the engine, andfor returning the said sequestered fuel quantity to the supply systemfor consumption in said engine when the original operating conditionsare restored.

An example of a fuel system to which the invention is particularlyadapted is described in US. Patent No. 2,758,579 to P. L. Pinotti, whichis characterized by a circulating header system that is selectivelysupplied by two dissimilar fuels, either singly or in predeterminableproportions, depending upon speed or load conditions of the engine. Onefuel is desirably a distillate for operation at idle or low loadconditions, and therother is a residual or heavy fuel which may be addedto the distillate or supplant it entirely at high load conditions orwhen the engine can assimilate it readily. The particular fuel, ormixture of fuels, in that system is continuously circulated in theheader until it is introduced by the injectors into the engine cylinder.

It has been found that sudden change in engine load, for example, arapid reduction from high load to idle, as may occur in a railway dieselengine that is directed onto a siding immediately after ascending a longgrade or after operating at high speed, will leave a quantity of a heavyfuel mixture or only heavy residual fuel in the fuel supply systemimmediately adjacent the injectors, for example, in the circulatingheader of PatentNo. 2,758,579, that is relatively unsuited to the lowload or engine idling condition. The engine, meanwhile, will requiresuch a low rate of fuel consumption under these circumstances that thisquantity of fuel, even if it is a fraction of a gallon, will require arelatively long time to be consumed. Under such conditions, undesirableresults, such as smoking, carbon deposits on injectors, or sparking, maysubsequently occur.

It is an object of this invention to provide a method and apparatus forrapidly sequestering a predetermined quantity of fuel from a fuelsystem, particularly of the type just described, at the time the load onthe engine is reduced to idle or a low output, so that the moredesirablefuel for the last-named condition will reach the injectors promptly andoperate the engine at its optimum condition. Thereafter, when the higherload or speed is to be resumed, this sequestered quantity will becontrollably returned to the fuel supply system, or circulating header,and blended withthe fuel therein to be consumed without adverselyaffecting the engine operations. Desirably, but not necessarily, thefunctioning ofv the sequestering means is interconnected with the enginethrottle or the load-governing mechanism. In any specific 2,911,958 IPatented Nov. 10, 1959 installation, the most advantageous arrangementand mode of operation will be apparent to one skilled in this art.

Another object is to provide a method and apparatus of the type justdescribed that is simple to operate and construct and is adapted toexisting installations of engine fuel systems without extensivemodifications.

These and other objects and advantages will be further apparent from thefollowing description and the attached drawing, which forms, a part ofthis specification and illustrates diagrammatically simple examples ofthe invention as applied to a circulating header internal combustionengine fuel system and to a non-return fuel system, each selectivelysupplied from two dissimilar fuel sources.

In the drawing, Figure 1 is a diagrammatic plan view illustrating anexample of the invention as applied to a circulating header type systemas may be employed on an electromotive (General Motors) diesel engine.

Figure 2 is a fragmentary diagrammatic plan view of part of thearrangement of Figure 1, which illustrates a non-return ornon-circulating header for supplying fuel to the engine injectors of thetype used on Baldwin and American Locomotive Company engines.

Figure 3 is an enlarged, fragmentary, diagrammatic view of one form ofmixing or proportioning valve that will introduce only one fuel or amixture of two fuels, depending on the engine throttle setting.

Referring to Figure 1 of the drawing, reference numeral 10 designatesgenerally in outline an engine, in this case an internal combustionengine of the compressionignition type, fitted with the usual banks offuel injectors 11. The inlets of injectors 11 are connected in parallelto an inlet conduit 12 and their outlets communicate with an outletconduit 13. A circulating pump 14 is connected between conduits 12 and13 by means such as connecting conduit 15 to provide what may be termeda circulating fuel header. As is customary in these injectors, fuel oilsupplied thereto through their inlets and not actually utilized orinjected into the respective engine cylinders, flows to the outlet, sothat, with the arrangement just described, there is a finite body orquantity of liquid fuel, the amount dependent upon the dimensions of thesystem, which fills that system and circulates to and through theseveral injectors.

' To supply dissimilar liquid fuels to the system just described, a pairof storage tanks 16 and 17 are provided, respectively, for distillateand residual fuel oil. Each is connected through its pump 18 and 19 andappropriate piping to a mixing point, which may be a selecting orproportioning valve 20, the operating means of which is suitablyconnected as shown by dotted line 21 to the throttle or governor 22 ofthe engine. Valve 20 is arranged to supply either fuel alone to thesystem or to mix them in any desired proportion. Figure 3 illustrates aform of three-way valve 20 that, in the position shown, will admit onlydistillate fuel from tank 16 to circulating header 15, as justdescribed. When it is rotated clockwise through about it admits onlyresidual fuel from tank 17. At intermediate positions, it varies theproportions by the respective port openings of the rotor 200 in a mannerwell known in the fluid control art. Alternatively, each pump may besuitably individually controlled by the governor or throttled to supplythe desired fuel quantity, in which case the valve 20 could be a simpleT or other means adapted to constitute a point of introduction of thefuel to the engine supply system. The outlet of valve 20 is connected tothe inlet conduit 12 of the circulating header. The specificconstruction and arrangement of the engine throttle 22 and proportioningvalve 20, as well as the usual filters, heaters, pressure regulators andthe like, are not a part of this invention and, hence, need nodiscussion'in this specification. Reference is made to US. Patent No.2,758,579 for a typical illustration of such details. 7

In order to provide a method and means for rapidly withdrawing andsequestering the liquid contents of the circulating header and injectorsystem, an accumulator chamber 23 is connected to conduit between outletconduit 13 and the inlet to' circulating pump 14 by means of a shortconduit 24. Accumulator 23 is a simple cylindrical container fitted witha; sliding piston 25 or other displ'aceable means, such as a flexiblediaphragm, for accumulating liquid in the left end 26 under theinfluence of a pressure differential or a resilient means, such as aspring. The opposite end 27 of accumulator 23 is suitably connected to athree-way valve 28 arranged to vent 27 to atmosphere through line 29,for example, when the accumulator is intended to withdraw a quantity ofliquid fuel from the circulating fuel system 12, 13, and 15 under thepressure existing therein by virtue of pumps 1'8'or' 19 D'esirably,valve 28 is connected through a time delay mechanism, generallydesignated 30, to the engine throttle valve or load governor 22 byappropriate means designated by the dotted line 31. This is soconstructed and arranged that Whenever the engine throttle or governor 2is actuated to reduce the fuel supply to the engine from high load to'anidle or low load condition, accumulator 23 functions as just describedto rapidly withdraw a predetermined quantity of the'liquid fuel fromthe'circulating header and sequester it until such a' time as isappropriate to return it to the header, as will be explained below. Inpractice, this quantity ma 'ra'nge from about 100% to 200% of the totalcapacity of the circulatingsys'te'm and injectors. V In the usualcase,when the load on the engine is rapidly reduced to idle or low condition,it is desirable to supply only distillate fuel until the high load orspeed condition is resumed. The cooperation of throttle 22 with valve 20provides such a supply, as that valve normally is'effec tive, eitheralone or in cooperation with conventional accessories, to preventpump'19 from adding residuum to the circulating header during thiscondition; L

After the low load or idling condition is past and high or full'loadengine operation is to'be rcsurnedythr'ottle 22 is adjusted to governthe supply of distillate and, if d esircd, residual fuelto the'circulating header in cooperation with valve 20 and-pumps 18 aiid 1 9.Tirnedelay mechanism 30 is adjusted to allow a reasonabletinieperiod toelapse, so'that it is assured that high load conditionswill continue,whereupon it'furictions to actuatevalve 23: to permit air or gas'undersuitable pressure froin al supply line 32 to enter end 27 of accumulator23 and returnpis ton 25 to its initial pQSiti n at the extreme left endof the accumulator. This displaces the sequestered" liquid fuel from end26 of the accumulator and returns it to the circulating fuel system 12,13, and 15 undercoriditions where its compositiomwhich may bepreponderantly'or entirely residuum, will not adversely affect theengine operation. p p i Referringnow to Figure 2, which illustrates theapplication of the invention to a non-return or noncirculating type fuelsupply system, reference numeral 1d designates generally and in outlinethe engine, on which is mounted a plurality of injectors 111which'receiv'e fuel from a conduit 112 supplied'from a' propo'rtio'ningvalve or mixing point 120'and introduce it into the engine cylinders.Conduit 112 fomts the fuel supply system and'contains thefinite quantityof liquid fuel already mentioned. To supply the two dissimilarliquidfuels to point 120, pumps 118 and 119 are provided, each with a suitabletank (not shown) corresponding to 18 and 19 of Figure l;

Accumulator chamber 123is connected to conduit 112 by short conduit 124,and its function, construction, mode of operation, and control by theengine throttle or load governor are otherwise identical with thearrangement of Figure 1. Accordingly, repetition of the descriptions al-.4 readygiven for .theseelements is deemed to be unnecessary for anunderstanding of the invention.

In conclusion, it will be appreciated that this invention comprehendsbroadly the provision of a method and means for withdrawing andsequestering a predetermined quantity of liquid fuel from the fuelsupply system of an internal combustion engine, which may be included ina circulating body .61- headei: system, or in a supply conduit system,undcr a phangein load or operating conditions of. the' eii e; forexample, low load or idle, that the said fuel characteristics wouldimpair the operation of engine and, thereafter, when the load oroperating conditions are appropriate, returning the said withdrawnsequesteredquantity to the system for consumption in the engine; Duringthe time interval when such an action has taken place, it iscomprehended that a more suitable fuel would be supplied to the engineunder the'load' conditions existing.

Although a simple embodiment has been illustrated and described withparticular referenceto an arrangement of a circulating header foracompression-ignition engine, exemplified by ,Patent No. ,2,758,579,.andan alternative non-circulating arrangement, it will be apparent that theinvention is not so. limited and that numerous changes could" be madewithout departing from its essential features. Accordingly, all suchchanges andmodifications that come within the scope of the appendedclaims are intendedto be'embraced' thereby.

I claim:

1'. In a method of operatingla'. compression-ignition engine on' amixture of two dissimilar liquid fuels in predeterminable proportions,said mixture being conti'nuously circulated in a conduit or the like incommunication with the fuel injection system ofvsaid engine, the stepsofwithdrawing the contents of said conduit into a confined chamber topermit said conduit to fill with substantiallyonly one of said'fuelswhen the load on said ngine'is reduced, supplying said one fuel to saidconduit during saidredu'ced load period, and subsequently returning saidwithdrawn portion to said circulating conduit when the load on'saidengine is increased.

2; Ina method of operating a compression-ignition engine on a mixture oftwo dissimilar liquid fuels in predeterminable' proportions, saidmixture being continuously suppliedto a conduit or the like incommunication with the fuel injection" system of said engine, the stepof withdrawing the contents of said conduit into a confined chamber to.permit said conduit to fill with substantially only one'of said'flielswhen the fuel supply to said engine is r'ed uced, supplying" said onefuel to said conduit during said reduced'fuel supply period,andsubs'equently returning said withdrawn'portidn to said conduit whenthe fuel supply tosaid engine is increased. I I

3'. In a method of selectively operating an internal combustienen'gineon one or both of two dissimilar liquid'fuel's'in' predeterniinableproportions, and in which a finite" quantity of said'fiiel' ismaintained in a closed systern betweena pointofintroduction and at leastone point of utilization, the steps of sequestering aprcdeterminoquantity of said'fuelfroin'said system whenthe loadon said'engine: isreduced'so'that substantially only one of said fuels'utilized in'sa'idengine, supplying substantially only said one fuel to saidfclosed systemduring said'reduccdlt'ia'dperid, and subsequently returning saidseq'tiestered quantitytosaid'system when the load on said engine isincreased; A p I 4. In" a method of operating an internal combustionengine aecording'to claim 3,"the added step of delaying the returnof'saidsequcstered quantity tosaid system for a predetermined period oftime after the load on said engine'is increased. I

5. In afuel system for'supplying amixture of two dissir'nilar liquidfuels to a. compression-ignition engine including a;he'ader chambercommunicating with the injector system of said engine, means forsupplying said mixture thereto, means for circulating said mixturethrough said chamber, and means for controlling the rate of fuel supplyto said engine; the combination comprising an accumulator forwithdrawing the mixture Within said chamber, means for supplyingsubstantially only one of said fuels to said header chamber to circulatetherein, and means responsive to the fuel supply control means of saidengine for actuating said accumulator and said lastnamed fuel supplymeans.

6. In a fuel system for supplying a mixture of two dissimilar fuels to acompression-ignition engine inciuding means tor maintaining a finitequantity of said fuel under pressure in a confined system between apoint of intro duction into said system and at least one point ofutilization in said engine, and means for regulating the rate of fuelsupply to said engine, the combination comprising an accumulatorresponsive to said regulating means for sequestering said finite fuelquantity, means for supplying thereafter substantially only one of saidfuels to said confined system, and means responsive to said regulatingmeans for discharging the sequestered fuel from said 0 accumulator intosaid confined system.

No references cited.

